Despite the tremendous popularity of social network sites both on the web and within enterprises, the relationship information they contain may be often incomplete or outdated. We suggest a novel crowdsourcing approach that uses a game to help enrich and expand the social network topology. The game prompts players to provide the names of people who have a relationship with individuals they know. The game was deployed for a one-month period within a large global organization. We provide an analysis of the data collected through this deployment, in comparison with the data from the organization's social network site. Our results indicate that the game rapidly collects large volumes of valid information that can be used to enrich and reinforce an existing social network site's data. We point out other aspects and benefits of using a crowdsourcing game to harvest social network information.